多片式衬底HFCVD系统沉积金刚石颗粒物理场的仿真优化

Simulation optimization of physical field of diamond particles deposited by multi-piece substrates HFCVD system

探索热丝化学气相沉积(hot filament chemical vapor deposition,HFCVD)合成高效优质的金刚石已成为研究热点。采用可提高金刚石颗粒单次沉积产量的新型多片式栅状衬底,应用FLUENT流体仿真软件,在原有单个出气口数量及进气总流量保持不变的情况下,优化传统模型,将单个进气口拆分成5个大小相等的进气口,对影响金刚石单晶颗粒均匀性的进气口数量和排布方式工艺参数进行仿真,对比分析HFCVD系统内气体的物理场。结果显示:4组优化模型均提高了衬底温度及流速的均匀性,有利于金刚石单晶颗粒的均匀生长,但对其沉积速率影响不显著;进一步分析优化模型的温度场,发现5个进气口及单个出气口分别位于反应腔体顶部和底部的中间位置时系统的温度差最低,最满足金刚石单晶颗粒在多片式硅衬底上均匀生长的条件。HFCVD金刚石单晶颗粒沉积试验验证了仿真结果的正确性。

Hot filament CVD method,which is used to synthesize high efficiency and high quality superhard abrasives,has become a research hotspot.Based on a new multi-piece grid substrate,which can increase the single deposition yield of micro-powder,and FLUENT,the fluid simulation software,the traditional model is optimized with unchanged number of single outlet and stable total intake flow but the single inlet is split into five equally sized inlet.The number and the arrangement of inlets that affect the process uniformity are simulated.The physical field of gas in the HFCVD system is compared and analyzed.Results show that the four optimized models all perform improved uniformity of substrate temperature and flow rate,which is conducive to the uniform growth of diamond single crystal particles,but the effect of diamond deposition rate is not significant.Further analysis on the temperature field of the optimized model indicates that the temperature difference of the system is the lowest with five inlets located in the middle top and a single outlet in the middle bottom of the reaction chamber,which satisfies the condition of uniform growth of diamond single crystal particles on multi-piece silicon substrate.Finally,CVD single crystal diamond particles are deposited to verify the reliability of the simulation.